Printing with TPU
TPU (Thermoplastic Polyurethane) is any class of polyurethane plastics with many properties, including elasticity, transparency and resistance to oil, grease and abrasion. Technically they are thermoplastic elastomers consisting of linear segmented block copolymers composed of hard and soft segments.Applications
TPU has many applications including automotive instrument panels, caster wheels, power tools, sporting goods, medical devices, drive belts, footwear, inflatable rafts, and a variety of extruded film, sheet and profile applications. TPU is also a popular material used for outer cases of mobile devices. It is also used to make keyboard protectors for laptops.
The temperature of the nozzle when printing TPU should be 210-240°C and the temperature of the heated bed should be 70-80°C. The use of the heated bed is recommended. Because the material is elastic, you need an extruder that is capable of printing such materials.
Printing TPU on Bowden design extruders is impossible, because with such printers we’re pushing the filament through the Bowden tube and because it is elastic you’re most likely to fail. We also need to make sure that the retraction is turned off, as this causes the material to be tensed and as a result the material is tearing in the extruder. Because we’re not using retraction, there will be stringing, which we can remove with a heat gun or manually.
As you may have learned by now, the print speed of the first layer should be a bit lower, because by doing so, we are ensuring the best first layer adhesion to the heated bed. The printing speeds should be low (up to 30% of the nominal speed of the printer), as this ensures slow extrusion and a reduced risk of tearing the material.
When printing elastic materials the flow rate has to be set a bit higher compared to printing with other materials.
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